Bordetella pertussis causes a serious disease of children called whooping cough. The current vaccine consists of killed whole cells of B. pertussis. This vaccine is quite effective in preventing disease in children, but is toxic due to its content of endotoxin and of various toxic moities of B. pertussis. The nature of the immunogen of B. pertussis most critical in protection has never been established. Furthermore, no simple, accurate test for the presence of this immunogen in vaccines is available. We know little about the nature of protective immunity in whooping cough. Immunity has been assumed to be humoral, but a contribution due to secretory immune mechanisms or to cellular mechanisms has not been ruled out. Our studies seek to provide direct evidence regarding the identity of the protective immunogens of B. pertussis. We also wish to test subcellulr vaccines, or vaccines lacking toxic components. Lastly, we want to investigate the nature of the protective immunity induced by vaccination and by natural infection.